Powder assisted thermochemical severing of reentrant sections of metal



June 13, 1950 E. MEINCKE POWDER ASSISTED THERMOCHEMICAL SEVERING 0F REENTRANT SECTIONS OF METAL Flled June 28 1949 INVENTOR EDWARD MEINCKE ATTORNEY Patented June 13, 1950 POWDER ASSISTED THERMOCHEMICAL SEVERING F REENTRANT SECTIONS OF METAL Edward Meincke, Summit, N..J'., assignor to The Linde Air Products Company,.acorporation of Ohio Application June 28, 1949, Serial No. 101,708- 2 Claims. (Cl. ES 9.6)"

This invention relates to the art of thermo chemically severing metal bodies by means of a stream of oxygen and at least one preheating flame, and more particularly to powder assisted thermochemical cutting of hollow and r'eent'rant sections of metal.

This application is a continuation-in-part of my applications Serial No. 547,062, filed July 28, 1944, now Patent Number 2,470,999, issued May 24, 1949, and Serial No. 681,352, filed July 3, 1946.

In the past it was necessary to maintain a relatively short and rather critical distance between the cutting blowpipe nozzle and the surface of the work in order to insure the uninterrupted progress of the cutting operation. It was even impossible to cut through hollow and reentrant sections, because the cutting action would not carry across any voids or air spaces within the work, or between the work and the blowpipe nozzle in excess of such critical distance. It also was necessary to swing the cutting blowpipe to take" care of the phenomenon known as cutting lag. Many complicated and expensive mechanical movements have been devised and are in use" for moving the blowpipe across the work, especially in the thermochemical cutting of steel bar stock.

The problem of flame cutting reentrant and hollow sections of carbon steel, such as channels, Z' bars, I-beams, rails, etc., and pipe has always been diilicult due to the need of closely following the surface contour of the shape or section to maintain the rather small critical distance between the end of the cutting nozzle and the surface of the work. Many devices and machines for doing this have been patented. Results and. production costs, however, have been less than satisfactory except where a large number of repetitive cuts could be made without making several machine adjustments. Cutting a kerf through hollow sections of carbon-steel also presents a' problem that has not been satisfactorily solved by using prior flame cutting equipment and processes, since the void or air space within the work interrupts the cutting action.

The main object of this invention is to provide a novel thermochemical severing process which solves such problems.

According to the invention, this is accomplished by supplying heated ferrous metal powderto a descending cutting oxygen stream, as disclosed and claimed, for example, in patent application Serial No. 547,062, filed July 28, 1944, now Patent Number 2,470,999, issued May 24, 1949, for Thermochemical metal removal, of which the present application is, in part, a continuation; and moving such powder-laden cutting stream transversely'across the work at a substantially constant speed without critical regard to the external surface contour or the internal shape thereof. The burning metal powder in and ad'- jacent the cutting oxygen stream has the effect of' greatly stretching out the preheating distance through the mass of air between the nozzle and the work, as well as through the work itself and any air space or void therein. The effective length of the preheating distance, axially of the cutting oxygen stream, can be varied by a proper selection of the size of the powder particles. In general, the greater the particle size, the greater the eifective preheating distance.

Practice of the invention has indicated that it is possible to cut in a single pass across work containing voids, or to carry successful cuts even when the distance between the nozzle and the work is greater than encountered in normal gas cutting. This falls into three principal categories': (1) Severing a metal body across one or more voids within such body of metal. (2) Severing metal bodies across voids or open spaces between such bodies of metal. (3) Severing pipes, railroad rails, structural shapes, such as channels, I-beams, H-beams, Z-bars, etc.

The amount of adjuvent metal powder necessary to effect the above results varies directly as (1)' the gap or space across which cutting is to be done; and (2) the alloy content, or type of metal composing the body. In the second case, a ratio of cutting oxygen in cubic feet per hour to adjuvant steel powder in pounds consumed of about 50-1 is necessary for cutting 18-8 stainless steel.- I-lowever, if cast iron or brass is to be out such ratio would decrease to about 30-1, and would rise to'about 100-1 for cutting a straight chrome steel or plain carbon steel.

The invention can be utilized for transversely severing in a single pass a series of irregularshaped members of metal lying substantially side by side, across voids or spaces in and/or between such members, and permits the maintenance of the cutting blowpipe, during the cutting stroke, at'a' constant level without following variations in the contour of the work, and in the same relative position axially of itself, i. e. without tilting, during the cutting operation.

In the drawing:

Fig. 1 is a fragmentary perspective view of apparatus carrying out an exemplification of the process;

Fig. 2 is a sectional view of 50 in Fig. 1; and

Figs. 3-4 are views similar to Fig. 2 of other applications of the improved cutting process.

In Fig. 1 a machine M on a horizontal track T is adapted to carry a vertically positioned cutting 55 blowpipe 0 along a horizontal path transversely above a pipe B of metal such as carbon steel having an internal air space l0. Adjuvant powder consisting mainly of iron particles, is supplied to the blowpipe 0 from a hopper H by compressed 60 gas such as an air stream, for example, delivered to the hopper from a suitable source under pressurethrough' a conduit A: asm'or'e fully disclosed the work being cut in the application Serial No. 547,062, new Patent No. 2,470,999, issued May 24, 1949; of which the present application is a continuation-in-part. The air stream picks up powder in the hopper and conducts it to the blowpipe through conduit P which is provided with a powder shut-off valve 12. Oxygen and fuel gas (acetylene, for example) are supplied to the blowpipe through conduits O and F, respectively. Patent 2,327,337 shows a suitable powder dispenser.

In operation the work B is progressively preheated along the cutting line and the stream of powder laden cutting oxygen S from blowpipe C progressively cuts, in a single pass, a kerf K in the pipe B as the blowpipe C is held in a vertical position and moved by the machine M in a horizontal or straight path transversely above the work, regardless of variations in the contour M of the top surface, and of the air space H) in the pipe, without losing the cut, by virtue of the adjuvant powder supplied to such stream S. The velocity of the cutting oxygen stream is not increased, but in fact may be decreased by the use of a larger sized nozzle with excellent results.

Tests have demonstrated that successful cutting can be accomplished with the nozzle set to clear the highest point on the work, and after starting the cut, propelling the nozzle along a straight line above an irregular surface, such as that of a Z-bar. Although some portions of the work were several inches below the cutting oxygen orifice of the nozzle the cut was not lost. A cutting oxygen consumption to powder consumption ratio of about 30-1 gives good results for cutting cast iron and brass. Likewise, a corresponding oxygen to powder ratio of about 100-1 proved satisfactory for cutting straight chrome steel with varying nozzle heights. Application of the same procedure to plain carbon steel showed that cuts could be maintained with the nozzle at distances up to 7 to 8 inches away from the work surface.

Fig. 3 shows how channels U may be cut according to the invention. In conventional oxyl-fuel gas cutting without powder, the cut would be lost due to the voids or spaces It between the channel flanges. However, the hot and burning adjuvant powder in the cutting oxygen stream S serves to carry the necessary preheat across the spaces 16 to maintain the cut, so that the progress of the cut is not interrupted.

Fig. 4 shows how conventional steel rails R may be progressively severed, according to the invention, without interruption of the cutting operating when advancing the powder-laden cutting stream across the air spaces between the head and base of the rail.

Preferred ratios Powder Flow Air Flow Ratios lb. powder oz./min. lb./min. cu. ft./hr. lb./min,

Oxygen Flow Ratios 1b. powder cu. ft./ln lb./m1n oxygen Velocity of the cutting oxygen stream preferably is 980 feet per second at the mouth of cylindrical bore nozzles and 1365 feet per second at month of high speed nozzles (e. g. those having divergent orifices).

The invention makes it possible: (1) to cut across voids in either carbon or stainless steels by the use of suitable metal adjuvant powder; (2) to successfully carry cuts through carbon steels where the distance between the nozzle and the surface being cut is as great as '7 or 8 inches, and where no effort is made to follow the contour of the top of the work; and (3) to thermochemically sever hollow and reentrant sections of metal in one pass.

Besides ferrous metal, such as steel powder, other combustible metal powders useful for carrying out the invention are ferromanganese, manganese, and mixtures thereof with iron and/or steel powder. However, any suitable metal adjuvant powder may be used. Metal powder consisting essentially of ferrous metal has been found to be non-toxic and entirely suitable for the purpose of this invention. In general, powder having a screen analysis like that disclosed by Wagner 2,451,422 is preferred.

When cutting copper or brass, a mixture of iron and aluminum powder can be used effectively. This is disclosed in my copending application Serial No. 94,264, filed May 19, 1949.

I claim:

1. Process of thermochemically cutting a metal member consisting of carbon-steel having a shape comprising a Web disposed in a plane substantially parallel to the direction of flow of a cutting oxy-- gen stream, and flanges connected to such web but spaced apart and projecting laterally from the web, which process comprises advancing a cutting oxygen stream at a constant speed along a path extending at right angle to the direction of flow of such stream, and adding sufficient adjuvant powder to such stream to support the cutting action through such flanges and the web of said carbon-steel member, said powder consisting mainly of ferrous metal.

2. Process of thermochemically cutting a metal member having a shape comprising a vertical portion disposed in a plane substantially parallel to the direction of iiow of a cutting oxygen stream, and horizontal portions connected to such vertical portion but spaced apart and projecting laterally from the vertical portion, which process comprises advancing a cutting oxygen stream at a constant speed along a path extending at right angle to the direction of flow of such stream, and adding sufiicient adjuvant powder to such stream to support the cutting action through such horizontal portions and the vertical portion of said metal member, said powder consisting mainly of ferrous metal.

EDWARD MEINCKE.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS OTHER REFERENCES Metals Handbook, 1939 edition, pages 930-935 inclusive, pub. by American Society for Metals Cleveland. Qhio. 

